propositional function

A propositional function (that is to say a definition) does not always determine a class.

(β) A propositional function is necessary when all its values are true.

Call it a propositional function; and, if φx be a propositional function, the undetermined variable x is the argument.

Now consider a propositional function Fχ in which the variable argument χ is itself a propositional function.

A 'propositional function' or 'norm' may be 'non-predicative.'